Apparatus for maintaining the desired temperature of liquids



June 15, 1943. M. H. oLs'rAD :TAL

APPARATUS Foa MAINTAINING THE DEsInnbTEMPEnATURE 0F LIQUxDs Filed Aug. 19. 1942 INVENTOR Patented June 15, 1943 APPARATUS FOR MAINTAINING THE DE- SIRED TEMPERATURE OF LIQUIDS Martin H. Olsta, Bayside, and Allan E. White Plains, N. Y.,l assignors .to vNiagara.` Blower Company, New York, N. Y., a corporation of New York Application August 19, 1942, serial No.- 455,394

7 claims. Y(ci. 25T-4) This invention relates to apparatusvfor main' of water, thereby to greatly veliuce the amount of taining the desired temperature of a fluid and more particularly is shown, as an example of its use, as embodied and carried out ina heat exchanger for maintaining the desired temperature of quenching oil used in tempering steel. -However, the invention can be used in conjunction -With uids other than quenching oils and 'the invention is therefore not to be construed as limited to any particular fiuid to be treated.

This application is a continuation-in part of our copending application ySerial No. 419,412, illed November 17, 1941, for Apparatus for maintaining the desired temperature of a. liquid, now

Patent No. 2,296,946; dated September 29, 1942. In the tempering of steel, the steel at temperatures as high as 2000 F. is quenched in a bath of quenching oil which must be maintained near the proper temperature in order that the cooling of' the steel, in tempering, be effected at a certain rate. The bath of quenching oil is heated by the batches of steel being tempered and in order to maintain the proper temperature of the quenching oil, the quenching oil must be continuously recirculated through a cooler so as to maintain the desired temperature of the quenching bath while tempering the steel. The Quenching oil may include a large percentage of lard oil .reduced and the capacity of the cooler greatly diminished.

With-oil cooling systemsnow in use, no acie-A quate provision is madefor dewaxing the cooling surface and also, with systems now in use.

while it is possible to cool the quenching -oi1 hath, no provision is made for heating the bath.

Therefore, at the start of the operation of tempering steel, or in 'shifting to' higher tempera ture quenching, it hasibeen thepracticefor the operator to pass a few*A batches of hot steel through the bath merely to bring the bath up to the desired quenching temperature. The passingl of hot steel merely to bring up the vtempera ture of the quenching bath to that desired involves, of course, waste labor and also the possible*v loss of a large quantity of steel in the event vthat *I* it cannot be retempered at the desired temperature.

It is one of ent invention 'to provide a simple and ei'iicient therprincipal objects of the pres-v apparatus adapted to' cool a nuid in-which the coolinz eifect is obtained frointhe evaporation such apparatus which is i'ullyl automatic inmaincooling water necessary for the operation of the apparatus. .Another object of the invention isto provide such apparatus in vwhichthe cooling eect is obtained from the evaporation of water and in which the temperaturen! the liquid being treated is maintained within very close/ limits.

Another object of the invention is to provide taining the desired temperature of the liquid being treated.

Y Another-,object of the invention is to provide asimple and effective control for the minimum temperature of the liquid being treated by the adjustment ci the character of the air supplied to the apparatus.

Another object of the such apparatus in w effected entirely au atically in response to the temperature of the spray water, beingr in turn responsive .to the temperature of the liquid'beins invention, is to provide treated. l

Another object is to provide such apparatus in which the amount of moisture evaporated to provide the cooling eilect is reduced to a minimum. v

Another object oi.' the invention is to provide for dewaxing the cooling surlsce, when used for cooling quenching oil," so as to insure the proper heat transfer between the cooling surface and the quenching yfoil at all times.

Another object of the invention is to provide for heating the quenching oil, when desired, so

esto bring it up to the proper temperature for use in tempering steel. and thereby avoid the necessity of passing batches of hot steel through l the quenching bath merely to bring it up to proper temperature.

Another object of the invention is to provide a simple and eective vmeans for maintaining any desired minimum temperature of the spray water winch is evaporated. thereby to provide a more exact control ofthe cooling euect of the. apparatus.

" 'Another object is to maintain the apparatus under auch!v conditions that no -substantiai amounts of lard oil are precipitated out on the cololing surface, when used for cooling quenching o Y e severe and constant use without getting out ci order or requirin's repairs. 7

RBSSU f ch such control can be vIn the. accompanying drawing:

Fig. 1 is a diagrammatic perspective view of a heat exchanger embodying and carrying out the invention.

Fig. 2 is a fragmentary, vertical, transverse section, taken on line 2-2, Fig. 1.

Fig. 3 is a fragmentary side elevation of a modified form of heat exchanger and showing a different way of supplying heat to the apparatus.

Fig. 4 is a fragmentary side elevation of a heat exchanger showing a further modied form of the invention.

Fig. 5 is a fragmentary view similar to Fig. 4 showing a still further modified form of the invention.

The heat exchanger shown, by way of example, in the raccompanying drawing is particularly 'designed for maintaining the desired temperature of the quenching oil used in tempering steel, in which it operates at most times to cool the quenching oil, provision also being made, however. for heating the quenching oil andalso to maintain the desired minimum temperature of the water used for cooling, through the heating means. 'Ihe apparatus shown includes a sheet metal casing 5 which is mounted upon a tank 6 forming the base of the casing, this tank 6 containing a body of water 1 which is evaporated to provide the cooling eiIect. The tank 6 is preferably extended beyond one end of the casing 5, as indicated at 3, and this extension is shown as provided with a top 9.

A plurality of fan housings I6 are mounted in the upper part of the casing 5, the inlets of these fan housings being in communication with. the interior of the casing 5 so as to exhaust air therefrom. -A common shaft II extends through the several fan housings l0 and is shown as driven by a motor I2 mounted onV a bracket I3 at one end of the casing 5. Within each fan housing the shaft II 'carries a fan vI4 of any operating lever 32 which projects downwardly and the bypass damper 3l is provided with a lever 33 which projects upwardly. The free ends of these levers 32 and 33 are connected by a bar 34, the central part of which is connected by a link 35 with the arm 36 of a damper motor 31, this damper motor 31 being shown as being mounted on a bracket 36 secured to the exterior of the duct 22. The control line 40 to the damper motor 31 connects with a thermostat 4I, the sensitive parts of which are immersed in the body 1 of spray Water in the tank 6, thisspray -water being heated, as hereinafter described, in

response to the temperature of the quenching oil or other liquid being cooled and which.

quenching oil leaves the apparatus through a return line 42, this return line discharging the quenching oil bath into the quenching tank (not shown). The quenching oil or other liquid to be treated is supplied' through a line 43, the

inlet and outlet lines 42, 4.3 for the quenching oil connecting with the headers of a bank ol' coils 44 arranged within the casing 5 immediately above the opening from the duct 23, these coils being thereby arranged in the path of the air drawn from the duct 23 and upwardly through the casing 5 by the fan wheels I4.

suitable construction, these fans drawing the air from the interior of the casing 5 `and discharg-A A horidischarging into a vertical duct 22 arranged in rear of the casing 5 and this vertical duct 22 being provided with a lower horizontal leg 23 which is in communication with the lower part of the casing 5 immediately above the tank 6. A cold air intake `duct 25 also discharges into the vertical duct 22, nthis cold air intake duct being preferably in horizontal alinement with the bypass air duct 2|.

Means are provided for delivering different proportions of cold outside air from the duct 26 and bypassed or return air from the duct 2l into the duct 22. For this purpose a fresh air damper 30 is arranged in the cold outside air duct 26 and a bypass damper 3l is arranged in the vertical air discharge duct 20 in position to close the opening into the bypass air duct 2|. This bypass damper 3l, when moved away from the opening into the bypass air duct, is also moved to .restrict the air discharge duct 20 thereby to reduce the amount of air exhausted to the atmosphere in relation to the amount of air recirculated through the bypass duct 2 I.

The fresh air damper 30 is provided with an Immediately below the bank of coils 44 a second bank of coils 45 is arranged, this second bank of coils 45 being supplied with steam from a steam line 46, the condensate being withdrawn from these coils through a line 41. The steam or other heating medium supplied to the coils 45 is under control of a valve 48 which is actuated in response to an immersion thermostat 49, the sensitive parts of which are immersed in the body of water 1 contained within the tank 6. The steam valve 48 can also be placed under manual control and for this purpose the immersion thermostat 49 is shown as connected to the steam valve 48 by a wire 50, and the other wires 5| and 52 connected, respectively, with the steam valve 48 and immersion thermostat 49 are shown as connected 'through a manual switch 53 with the main power lines 54 and 55. While the steam -coil 45 is shown for supplying heat, it will be understood that heat could be supplied by other means, as by a steam ejector 15in the recirculating water line 6I, as shown in Fig. 3, or by a heating coil 45a immersed in the water 1 in the tank 6, as shown in Fig. 4, or by a coil 45h arranged abovethe cooling coil 44, as shown in Fig. 5. Further, the control of the steam or other heating medium could be made responsive to an immersion thermostat 16, the sensitive parts of which are immersed in the quenching oilv or other liquid leaving the apparatus through the line 42, as shown in Fig. 4. Y

TheIwater 1 to the tank 6 can be supplied in any suitable manner and is shown as maintained at a constant'level by an overiiow connection 56 in the upper part of the tank 6, this overflow 56 leading to a drain line 51 connected with the bottom part of the tank 6. A drain valve 58 is provided in the drain line 51 between the tank 6 and the connection of this drain line 51 with the overflow line 56.

'I'he water 1 in the tank 6 is withdrawn by a centrifugal spray water pump 60 and is discharged through a vertical pipe 6i into a horizontal pipe 62 extending lengthwise through the interior of the casing above the bank of coils 44. This pipe 62 carries a suitable number of branch pipes 63, each of which carries a down- 4 flushed with water.

fore be seen that the immersion thermostat 4| wardly discharging nozzle $4.v The nozzles 64 are arranged above the bank of coils 44 which carry the quenching oil or other liquid to be cooled so that .these coils 44 are yconstantly The excess water from the coils 44 falls back into the tank 6 to be again recirculated by thespray water pump 60.

Operation Assuming that the quenching oil is being used for tempering steel and that the heat exchanger forming the subject of the invention is operating under heavy cooling load conditions, this hot quenching oil enters the bank of cooling coils 44 from the supply line 43 and is returned to the tempering bath through the'line 42. The quenching oil so passing through the bank of coils 44 is arranged in the stream of air which, under heavy cooling load conditions, is drawn by the fan wheels I4 from the cold air intake duct 28 through the vertical duct 22 and horizontal leg 23 intothe bottom o f the casing '5, this cold outside air being drawn vertically upward through the casing 5 and discharged by the fan wheels i4 into the air discharge duct 2o. At the same time the body of watery i in the tank 6 is being pumped by the spray water pump 6o. through the pipes Si, B2 and 63 and is sprayed onto the bank of coils 44 by the nozzles t, the excess spray water collecting in the'tank d. The bank of coils 6 carrying the I hot quenching oil is thereby ooded with water,

this water evaporating on these coils; the coils Q4 tending to assume the wet bulb temperature.

of the air drawn upwardly through these coils by the fan'lwheels id. The quenching oil passing through the bank of coils 4t is thereby subjected to evaporative cooling and leaves through, I

the return line d2 in a cooled condition.

With a decrease in the cooling load uponnthe apparatus, as occurs between withdrawing a tempered batch of steel and the introduction of a batch of hot steel into the bath of quenching oil to be tempered, the falling temperature oi the quenching oil passing through the bank of coils dd effects a corresponding drop in temperature of the water sprayed over this coil and hence actuates the thermostat il and the damper motor 3l connected to this thermostat through` the control line to move the fresh air damper 3@ toward its closed position and the bypass damper 3i toward its open position. It will be 1 -intake duct 2t,v through the vertical duct 22 and in the spray water maintains a constant minimum temperature of the quenching oil by the inverse operation of the bypass damper 3l and fresh air 'damper 30, a falling temperature of the quenching oil or other liquid being treated.

the cold fresh air damper 30. This modulating control of the dampers 30 and 3i allows the intermediate position of these dampers to hold a constant minimum temperature of the quenching oil by the use of bypassed air and tempered cold fresh air. The bypassing of the necessary amount of air from the air discharge duct 20 to the bottom of the casing 5 in so maintaining a constant'minimum temperature ofthe quenching oil or other liquid being treated also keeps the amount of evaporated moisture to a minimum. The arrangement of the bypass damper 3l in the air discharge duct 20 also serves to reduce the amount of air exhausted through the outlet of the discharge duct 20 with an increase in the amount of bypassed air returned to the bottom of the casing 5.

- Ijl'he primary purpose of the immersion thermo-- stat i9 in the spray water tank 6 (or the thermostat 16, Fig. 4, in the quenching oil) is to keep the water temperature above a predetermined minimum. With quenching oils, this minimum tain, through the steam coils 45, this iminimumI temperature of the spray'water, the deposit of wax in the coils d4 is reduced to a minimum since it has been ascertained that at temperatures above 1i'. practically no, lard oil will deposit out of quenching oils.

In the event that the temperature of the quenching oil drops below that required for properly'tempering the steel, as at the start of operation or in an extended period between teme pering operations, the immersion thermostat i9 is actuated by the lowering temperature of the water 'i in the tank 6 to open the steam valve de and admit, steam to the steam coils d5. This thermostat 5,9 serves to maintain a constant minimum temperature of the spray water. Under these conditions, the immersion thermostat 6l has moved the fresh air damper 30 to its fully closed position and the bypass damper @t to its fully opened position and hence the air heated by the steam coils d5 is continuously recirculated by the fan wheels I d, through the air discharge duct'Z, bypass duct 2i, vertical duct 22, and horizontal leg 2s to the bottom of vthe casing 5, this air moving upwardly through the bank of coils it carrying the quenching oil or other liquid being treated so as to heat the same.-

' Since' this recirculating air is saturated with its horizontal leg 28. into the bottom of the cas= The same eect is obtained through the thermostat '56, Fig. 4. l

If the cooling coils Q4 which carry'the quenching oil become waxedup internally due tothe deposit of lard oil in the form of a wax therein,

' the heat exchanger can be manually ladjusted tooperate in the same way as when the quench- A ing oil is below the set temperature as just described. 'I'hus, to dewax the cooling coil M, the fresh air damper 30 is held closed, the recirculated air damper is held open and steam, undercontrol of the manual switch 53, ist admitted to the steam coil 45. The air being recirculated through the casing is thereby heated so as to melt the wax in the cooling coils M, this Wax being carried away with the quenching oil.

While theinvention has been described particularly in conjunction with the cooling of quenching oils, it will be understood that it is not limited to this particular use but may be used in conjunction with any liquid to be treated as indicated in the accompanying claims.

From the foregoing it will be seen that the present invention provides a simple and eilicient apparatus for maintaining the desired temperature of a uid, such as quenching oil, within very close limits; which has a high cooling capacity with amlnimum consumption of cooling water; and which will .prevent the fluid being treated from dropping below the desired mini- Further, when the cooling i range, comprising means forming a chamber having an air inlet and an air outlet, a fanarranged to force a stream of air from-said inlet, through said chamber and out through said outlet, a cooling coil arranged in the stream of air passing through said chamber, means for discharging and distributing a stream of water over said cooling coil to wet the'exterior of said cooling coil and to evaporate and absorb heat therefrom, means for continuously conducting the said stream oi fluid to be cooled through said cooling through heat derived from said stream of iluid passing through said cooling coil, means for applying heat to said stream of fluidl and thermostat means responsive to the temperature of one of said streams to adjust said means for applying heat to prevent thev temperature of said fluid in said cooling coil from falling below said temperature range.

3. A heat exchange device' for'maintaining a fluid in a selected temperature range determined by the character of the'iluid by cooling a stream of said iluid and preventing the temperature thereof from falling below said temperature range, comprising means forming a chamber` having an air inlet and an air outlet, a fan arranged to force a stream of air from said inlet, through said chamber and out through said outlet. a cooling coil arranged inthe stream of air passing through said chamber, means for discharging and distributing a stream of 'vater over said cooling coll to wet the exterior of said cooling coil and to evaporate and absorb heat therefrom, means for continuously conducting the said vstream of fluid to be cooled through said cooling coil, said streams of air and water being normally heated through heat derived from said stream of fluidpassing through said cooling coil,

bypass means for conducting a part of the stream of air leaving said chamber back to said air inlet,

'coil from falling below said temperature range.

4. A heat exchange device for maintaining a fluid in a selected temperature range determined by the character of the duid by cooling a stream of said iluid and 'preventing the temperature thereof from falling below said temperature range, comprising means forming a chamber having an air inlet and an air outlet, a fan arranged to force a stream of air from said inlet, through coil, said streams of air and water being norlow said temperature range.

. 2. A heat exchange device for maintaining a uid in a selected temperaturg :ange determined by the character of the iluidby cooling a stream of said fluid and preventing the temperature thereof from falling below said temperature range, comprising means forming a chamber having an air inlet and an air outlet, a fan arranged to force a stream .of air from said inlet, through said chamber and. out through said outlet, a

I cooling coil arranged in the stream of air passing through said chamber, means for dlschargingfand distributing a stream of water over said cooling coil to wet the exterior of said cooling coil and to evaporate and absorb heat therefrom, means for continuously conducting the said stream of liuid to be cooled through said, cooling coil, said streams of air and water being normally heated said chamber and out through said outlet, a cooling coil arranged in the stream of air passing through said chamber, means for discharging and distributing a stream of water over said cooling coil to wet the exterior of said cooling coil and to evaporate andabsorb heat therefrom, means for continuously conducting the said stream of fluid to be cooled through said cooling coil, bypass means for conducting a part of the stream of -air leaving said chamber back lto said air inlet, means for controlling the amount of -air returning through said bypass means, a heating coil arranged in the stream of air passing through said chamber, said streams of air and water being normally heated through heat derived from said stream of iluid passing through said cooling coil, means for conducting a heating medium through said heating coil to heat the air passing said cooling coil. and thermostat means responsive to thetemperature of one of said streams to adjust said heating medium conducting means te prevent the temperature of said l fluid in said cooling coil from falling below said temperature range.

5'. A heat exchange device for maintaining a fluid in a selected temperature range determined by the character ci' the fluid -by cooling a stream of said fluid and preventing the temperature thereof from falling below said temprature range, comprising means forming a chamber having an air inlet and an air outlet, a fan arranged asados@ to force a stream of air from said inlet, through said chamber and out through said outlet, a cooling coil arranged in the stream of air passing through said chamber, means for discharging and distributing water over said coo gl coil to wet the exterior of said cooling coil an to evaporate and absorb heat therefrom, means for continuously conducting the said stream of uid to be cooled through said cooling coil, means for applying heat to said stream of liquid, and thermostat means directly responsive to the temperature ot said water t0 adjust said means for applying heat to prevent the temperature thereof from falling below said temperature range.

6. A heat exchange device for maintaining a luid, having e, component which congeals when cooled below a certain temperature, in a selected temperature range above said congealing temperature by cooling a stream of said duid and preventing the temperature thereof from iallins below said temperature range, comprising means forming a chamber having an air inlet and an air outlet, a fan arranged to force a stream of air from said inlet, through said chamber' and out through said outlet, a cooling coil arranged in the stream of air passing through said chamber, means for discharging and distributing a stream of water over said cooling coil to wet the exterior ci said cooling coil and to evaporate and absorb heat therefrom, means for continuously conducting the said stream of huid to be Y means responsive tothe said streams to adjust said meansv for applyingv cooled through said cooling coil, said streams of v air and Water tbeing normally heated through heat derived from said stream of duid passing cooling coil, means for applying duid, and thermostat temperature of one of through said heat to said stream oi temperature of said duid in heat to prevent the falling below said temperasaid cooling coil from ture range.

' 7. A heat exchange device for maintaining a uid in a selected temperature range determined by the character of the fluid by cooling a stream yof said duid' and preventing the temperature thereof from falling below said temperature range, comprising means `forming a chamber having an air inlet and an air outlet, a fan arranged to force a stream ofair from said inlet, through said chamber and out through said outlet, a cooling coil arranged in the stream of air passing through said chamber, means for discharging and distributing a streamer water vover said cooling coilto wet the exterior of said cooling coil and to evaporate and absorb heat therefrom,

means for continuously conducting' the said stream of fluid to be cooled through said cooling coil. said streams of air and water normally being heated throimh heat derived i'rom said stream ,of uid passing through said cooling coil, means for applying heat directly to said water, and thermostat means responsive to the' temperature of one of said streams" to adiust said means for applying heat to said water to prevent the temperature of said huid in said cooling coil from falling below said temperature range.

- MARTIN H. OLSTAD. 

